For First Responders, EVs Offer New Hazards

An electric vehicle's batteries, weight distribution, and other features change the way first responders must react to an emergency, whether they're putting out fires or trying to pull people out after a crash.

PM has spent some timecruising in a 2012 Mitsubishi i-MiEV, and driving it taught us some of the real-world quirks of owning an EV. Ron Moore learned a lot from getting his hands on an i-MiEV, too. But Moore's lessons came from ripping the thing apart.

Moore is a training consultant for the National Fire Prevention Association. He, along with a hand-picked team of firefighters, systematically tore apart a donated 2012 i-MiEV last month to educate emergency personnel on the complications high-voltage batteries and electrical systems present.

"It was a perfect opportunity for us," Moore tells PM. "We were unlimited in what we could do to it."

High Voltage

Where an ordinary car carries a 12 V battery, an EV might have more like 330 volts in its system, Moore says. That not only presents an increased immediate danger to first responders, but also puts new kinks into how they ensure a car is completely shut down.

Typically, firefighters disconnect the battery to kill any live wires within the vehicle, Moore says. But with EVs and hybrids, this isn't the case. Just disconnecting the 12V battery from the Mitsubishi does nothing to kill the power, Moore says. The car's larger 330 V lithium-ion battery is supplying power to both the vehicle's drivetrain and accessories.

"There is a very distinct sequence that you have to go through to get the high-voltage as well as the 12V electrical systems shut down," he says. Before firefighters even think about touching the smaller 12V battery, they need to kill the ignition. Cut power from the high-voltage battery and you cut power to the entire car. "That's different than what we're used to," he says.

For cases where first responders can't access the cabin, manufacturers have other built-in ways to kill the ignition from the outside. "Most of the manufactures come up with at least one alternate if not two," Moore says. On the i-MiEV, for example, rescuers can pull out all of the fuses from a box within the engine bay, dropping the relays to the battery and killing the high voltage. If the fuses aren't accessible, there's a secondary backup plan: a specifically designed and clearly identified "cut loop" inside the engine bay that responders can sever to kill the power.

Weight Distribution

With floorpan-mounted batteries, EVs and hybrids tend to throw their weight around differently than their internal-combustion cousins. "This is a trend that we're seeing, where the manufacturers want to get a larger battery—more cruising range—and they don't want to take your trunk space. So they're going beneath the floorpan," Moore says.

That changes how first responders deal with a flipped car. While a majority of cars have engines mounted in the front of the vehicle—causing them to settle on their hoods if flipped—the low, mid-mounted batteries of EVs keep them level, and more importantly, unstable. "Those floorpan-mounted batteries are really going to change the seriousness of a lean," he says. One wrong nudge and the vehicle could flip on nearby rescuers, and possible injury the people inside.

In one instance with the i-MiEV, when Moore and his team tried to reorient the vehicle from completely upside down to its side, the weight of the battery caused the vehicle to abruptly flop back onto its wheels. "I have never had a car do that," said Moore. "It was like that Weeble toy. It wanted to right itself."

First responders will need to employ a new set of stabilization techniques. "We're going to have to look at changing the way we think about stabilization of side-resting and roof-resting vehicles with floorpan batteries," he says. "We have current tools and techniques that we can deal with it, but it's just going to be a bit more challenging."

Battery Blockage

The battery also complicates first responders' mission of extracting trapped victims from a vehicle. Normally, rescuers will attempt to move crushed or failed parts of the car out of the way to help extract a trapped occupant—which sometimes requires going through the floor if they can't go through the sides, Moore says. "We're not going to be able to do that as readily with floorpan-mounted, high-voltage batteries," he says. "The floor has to be treated with a degree of respect. You don't want to bend it, crush it, or puncture it with a rescue tool for fear of direct contact with the cells of the lithium ion battery."

Roadblock as it may be, going through the floor is only one of the many ways firefighters can free a trapped passenger. Typically, the first option is go through the A-pillar—the front-most pillar which holds the windshield—which on the i-MiEV is completely accessible Moore says. "[Going through the floor] is just a backup plan for a very common job," he says. "But typically, 95 percent of the time we can get the work done using that outside area."

Moore says the first responders will be able to adapt their tactics to deal with whatever's out there on the road. His major concern, however, is making sure those responders know exactly what they're dealing with. And unless firefighters and police have an encyclopedic knowledge of every hybrid and EV, that won't be easy. "It's an impossible situation," he says. "You're talking a million responders and cars coming out every six months."

To help rescuers out, a new Society of Automotive Engineers proposal aims to mandate that auto manufacturers place three exterior markers on the rear and sides of the vehicle—or alternatively, a single identifier next to the ignition switch—to distinguish it as an EV or hybrid. "Before we can deal with an electric or hybrid, we need to know that we're dealing with those vehicles," he says. "So identification is the foundation of what our changes will be."